Data transmission method, terminal device, and network device

ABSTRACT

A data transmission method, including: receiving, by a terminal device on a first time domain resource, at least one piece of downlink data sent by a network device; and sending receiving status information to the network device on a second time domain resource. A transmission time interval of any piece of downlink data is less than a transmission time interval of the receiving status information, and the transmission time interval of the any piece of downlink data is less than 1 ms. According to the data transmission method, a transmission time interval of downlink data and a time interval between a sending time of the receiving status information and a receiving time of the at least one piece of downlink data are shortened, thereby reducing a latency.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2016/073335, filed on Feb. 3, 2016, which is hereby incorporatedby reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the field of wireless communicationstechnologies, and in particular, to a data transmission method, aterminal device, and a network device.

BACKGROUND

In a Long Term Evolution (LTE) system, after receiving downlink datasent by a network device, a terminal device needs to send hybridautomatic repeat request-acknowledgement (HARQ-ACK) feedback informationto the network device. If the downlink data is correctly received, theterminal device returns acknowledgement (ACK) information; if thedownlink data is not correctly received, the terminal device returnsnon-acknowledgement (NACK) information. The HARQ-ACK feedbackinformation may be carried on a physical uplink control channel (PUCCH)or a physical uplink shared channel (PUSCH).

In a wireless communications system, a latency is one of importantfactors affecting user experience. In addition, emerging of newservices, such as a related service of the Internet of Vehicles, imposesan increasingly harsh requirement on a low latency. Therefore, in anexisting LTE system, a transmission mechanism based on a one-subframetransmission time interval (TTI) cannot meet a demand for a low-latencyservice. How to reduce a latency becomes a problem to be resolvedurgently.

SUMMARY

Embodiments of the present invention provide a data transmission method,a terminal device, and a network device, so as to reduce a latency in acommunications system.

To resolve the foregoing technical problem, the embodiments of thepresent invention disclose the following technical solutions.

According to a first aspect, the present disclosure provides a datatransmission method, including: receiving, by a terminal device, atleast one piece of downlink data on a first time domain resource; andsending, by the terminal device, receiving status information on asecond time domain resource, where the receiving status information isused to indicate a receiving status of the at least one piece ofdownlink data, a time interval between the second time domain resourceand the first time domain resource is less than 4 milliseconds, atransmission time interval of the receiving status information isgreater than a transmission time interval of any piece of downlink datain the at least one piece of downlink data, and the transmission timeinterval of the any piece of downlink data is less than 1 millisecond.

According to the data transmission method provided in the first aspect,a transmission time interval of downlink data and a time intervalbetween a sending time of the receiving status information and areceiving time of the at least one piece of downlink data are shortened,thereby reducing a latency. In addition, a transmission time interval ofuplink data is greater than the transmission time interval of downlinkdata. This enhances performance for receiving the receiving statusinformation, and increases a probability that a network device correctlyreceives the receiving status information returned by the terminaldevice.

With reference to the first aspect, in a first possible implementationof the first aspect, a length of the transmission time interval of theany piece of downlink data in the at least one piece of downlink data is4 symbols or 3 symbols, and the transmission time interval of thereceiving status information is 0.5 ms; and the first time domainresource is a timeslot n−2 or a timeslot n−3 and the second time domainresource is a timeslot n, where the timeslot n−2 is a second timeslotcounted backward from the timeslot n, and the timeslot n−3 is a thirdtimeslot counted backward from the timeslot n.

With reference to the first aspect, in a second possible implementationof the first aspect, a length of the transmission time interval of theany piece of downlink data in the at least one piece of downlink data is2 symbols or 1 symbol, and the transmission time interval of thereceiving status information is 0.5 ms; and the first time domainresource is a timeslot n−2 and the second time domain resource is atimeslot n, where the timeslot n−2 is a second timeslot counted backwardfrom the timeslot n.

With reference to the first aspect or the second possible implementationof the first aspect, in a third possible implementation of the firstaspect, the method further includes: if the terminal device fails toreceive one or more pieces of downlink data in the at least one piece ofdownlink data on the first time domain resource, receiving, by theterminal device, the retransmitted one or more pieces of downlink dataon a third time domain resource, where the third time domain resource isa timeslot n+2 or a timeslot n+3, the timeslot n+2 is a second timeslotcounted forward from the timeslot n, and the timeslot n+3 is a thirdtimeslot counted forward from the timeslot n.

With reference to the first aspect, in a fourth possible implementationof the first aspect, the transmission time interval of the any piece ofdownlink data in the at least one piece of downlink data is 0.5 ms, andthe transmission time interval of the receiving status information is 1ms; and the first time domain resource is a subframe n−2 or a subframen−3 and the second time domain resource is a subframe n, where thesubframe n−2 is a second subframe counted backward from the subframe n,and the subframe n−3 is a third subframe counted backward from thesubframe n.

With reference to the fourth possible implementation of the firstaspect, in a fifth possible implementation of the first aspect, themethod further includes: if the terminal device fails to receive one ormore pieces of downlink data in the at least one piece of downlink dataon the first time domain resource, receiving, by the terminal device,the retransmitted one or more pieces of downlink data on a third timedomain resource, where the third time domain resource is a subframe n+2or a subframe n+3, the subframe n+2 is a second subframe counted forwardfrom the subframe n, and the subframe n+3 is a third subframe countedforward from the subframe n.

With reference to any one of the first aspect, or the first to the thirdpossible implementations of the first aspect, in a sixth possibleimplementation of the first aspect, the receiving status information iscarried on a physical uplink control channel PUCCH, and the transmissiontime interval of the receiving status information is 0.5 ms; and thesending, by the terminal device, receiving status information on asecond time domain resource includes: sending, by the terminal device, aPUCCH demodulation reference signal DMRS in the first N successivesymbols of the second time domain resource, and sending the PUCCH in 7-Nsymbols or 6-N symbols of the second time domain resource, where N is 1,2, or 3.

With reference to any one of the first aspect, or the first to the thirdpossible implementations of the first aspect, in a seventh possibleimplementation of the first aspect, the receiving status information iscarried on a PUCCH, the transmission time interval of the receivingstatus information is 0.5 ms, the PUCCH includes a first PUCCH and asecond PUCCH, and a PUCCH DMRS includes a first PUCCH DMRS and a secondPUCCH DMRS; and the sending, by the terminal device, receiving statusinformation on a second time domain resource includes: sending, by theterminal device, the first PUCCH and the first PUCCH DMRS in the firstM1 symbols of the second time domain resource, where the first PUCCH andthe first PUCCH DMRS occupy a first frequency domain resource in afrequency domain; and sending, by the terminal device, the second PUCCHand the second PUCCH DMRS in the last M2 symbols of the second timedomain resource, where the second PUCCH and the second PUCCH DMRS occupya second frequency domain resource in the frequency domain, and if eachtimeslot includes 7 symbols, M1 is 3 and M2 is 4, or M1 is 4 and M2 is3.

According to a second aspect, the present disclosure provides a datatransmission method, including: sending, by a network device, at leastone piece of downlink data on a first time domain resource; andreceiving, by the network device, receiving status information on asecond time domain resource, where the receiving status information isused to indicate a receiving status of the at least one piece ofdownlink data, a transmission time interval of the receiving statusinformation is greater than a transmission time interval of any piece ofdownlink data in the at least one piece of downlink data, thetransmission time interval of the any piece of downlink data is lessthan 1 millisecond, and a time interval between the second time domainresource and the first time domain resource is less than 4 milliseconds.

According to the data transmission method provided in the second aspect,a transmission time interval of downlink data and a time intervalbetween a sending time of the receiving status information and areceiving time of the at least one piece of downlink data are shortened,thereby reducing a latency. In addition, a transmission time interval ofuplink data is greater than the transmission time interval of downlinkdata. This enhances performance for receiving the receiving statusinformation, and increases a probability that the network devicecorrectly receives the receiving status information returned by aterminal device.

With reference to the second aspect, in a first possible implementationof the second aspect, a length of the transmission time interval of theany piece of downlink data in the at least one piece of downlink data is4 symbols or 3 symbols, and the transmission time interval of thereceiving status information is 0.5 ms; and the first time domainresource is a timeslot n−2 or a timeslot n−3 and the second time domainresource is a timeslot n, where the timeslot n−2 is a second timeslotcounted backward from the timeslot n, and the timeslot n−3 is a thirdtimeslot counted backward from the timeslot n.

With reference to the second aspect, in a second possible implementationof the second aspect, a length of the transmission time interval of theany piece of downlink data in the at least one piece of downlink data is2 symbols or 1 symbol, and the transmission time interval of thereceiving status information is 0.5 ms; and the first time domainresource is a timeslot n−2 and the second time domain resource is atimeslot n, where the timeslot n−2 is a second timeslot counted backwardfrom the timeslot n.

With reference to the first or the second possible implementation of thesecond aspect, in a third possible implementation of the second aspect,the method further includes: if the receiving status informationindicates that one or more pieces of downlink data in the at least onepiece of downlink data fail to be received, retransmitting, by thenetwork device, the one or more pieces of downlink data on a third timedomain resource, where the third time domain resource is a timeslot n+2or a timeslot n+3, the timeslot n+2 is a second timeslot counted forwardfrom the timeslot n, and the timeslot n+3 is a third timeslot countedforward from the timeslot n.

With reference to the second aspect, in a fourth possible implementationof the second aspect, the transmission time interval of the any piece ofdownlink data in the at least one piece of downlink data is 0.5 ms, andthe transmission time interval of the receiving status information is 1ms; and the first time domain resource is a subframe n−2 or a subframen−3 and the second time domain resource is a subframe n, where thesubframe n−2 is a second subframe counted backward from the subframe n,and the subframe n−3 is a third subframe counted backward from thesubframe n.

With reference to the fourth possible implementation of the secondaspect, in a fifth possible implementation of the second aspect, themethod further includes: if the receiving status information indicatesthat one or more pieces of downlink data in the at least one piece ofdownlink data fail to be received, retransmitting, by the networkdevice, the one or more pieces of downlink data on a third time domainresource, where the third time domain resource is a subframe n+2 or asubframe n+3, the subframe n+2 is a second subframe counted forward fromthe subframe n, and the subframe n+3 is a third subframe counted forwardfrom the subframe n.

With reference to any one of the second aspect, or the first to thethird possible implementations of the second aspect, in a sixth possibleimplementation of the second aspect, the receiving status information iscarried on a physical uplink control channel PUCCH, and the transmissiontime interval of the receiving status information is 0.5 ms; and thereceiving, by the network device, the receiving status information on asecond time domain resource includes: receiving, by the network device,a PUCCH demodulation reference signal DMRS in the first N successivesymbols of the second time domain resource, and receiving the PUCCH in7-N symbols or 6-N symbols of the second time domain resource, where Nis 1, 2, or 3.

With reference to any one of the second aspect, or the first to thethird possible implementations of the second aspect, in a seventhpossible implementation of the second aspect, the receiving statusinformation is carried on a PUCCH, the transmission time interval of thereceiving status information is 0.5 ms, the PUCCH includes a first PUCCHand a second PUCCH, and a PUCCH DMRS includes a first PUCCH DMRS and asecond PUCCH DMRS; and the receiving, by the network device, thereceiving status information on a second time domain resource includes:receiving, by the network device, the first PUCCH and the first PUCCHDMRS in the first M1 symbols of the second time domain resource, wherethe first PUCCH and the first PUCCH DMRS occupy a first frequency domainresource in a frequency domain; and receiving, by the network device,the second PUCCH and the second PUCCH DMRS in the last M2 symbols of thesecond time domain resource, where the second PUCCH and the second PUCCHDMRS occupy a second frequency domain resource in the frequency domain,and if each timeslot includes 7 symbols, M1 is 3 and M2 is 4, or M1 is 4and M2 is 3.

According to a third aspect, the present disclosure provides a terminaldevice, including a receiver and a transmitter. The terminal device isconfigured to perform the data transmission method provided in theimplementations of the first aspect.

According to a fourth aspect, the present disclosure provides a networkdevice, including a transmitter and a receiver. The network device isconfigured to perform the data transmission method provided in theimplementations of the second aspect.

It can be learned from the foregoing technical solutions that, accordingto the data transmission method provided in the embodiments of thepresent invention, the terminal device receives, on the first timedomain resource, the at least one piece of downlink data sent by thenetwork device; and then sends the receiving status information to thenetwork device on the second time domain resource. The transmission timeinterval of the any piece of downlink data is less than the transmissiontime interval of the receiving status information, and the transmissiontime interval of the any piece of downlink data is less than 1 ms. Inaddition, the time interval between the second time domain resource andthe first time domain resource is less than 4 ms. According to the datatransmission method, a transmission time interval of downlink data and atime interval between a sending time of the receiving status informationand a receiving time of the at least one piece of downlink data areshortened, thereby reducing a latency. In addition, a transmission timeinterval of uplink data is greater than the transmission time intervalof downlink data. This enhances performance for receiving the receivingstatus information, and increases a probability that the network devicecorrectly receives the receiving status information returned by theterminal device.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings in the specification that are a part of thisapplication are used for further understanding of the presentdisclosure. Example embodiments in the present invention anddescriptions thereof are intended to interpret the present disclosureand do not constitute any inappropriate limitation to the presentdisclosure.

FIG. 1 is a schematic diagram of a wireless communications networksystem according to an embodiment of the present invention;

FIG. 2 is a flowchart of a data transmission method according to anembodiment of the present invention;

FIG. 3 is a schematic diagram of a HARQ time sequence according to anembodiment of the present invention;

FIG. 4 is a schematic diagram of another HARQ time sequence according toan embodiment of the present invention;

FIG. 5 is a schematic diagram of another HARQ time sequence according toan embodiment of the present invention;

FIG. 6 is a schematic diagram of another HARQ time sequence according toan embodiment of the present invention;

FIG. 7 is a schematic diagram of still another HARQ time sequenceaccording to an embodiment of the present invention;

FIG. 8 is a schematic diagram of still another HARQ time sequenceaccording to an embodiment of the present invention;

FIG. 9 is a schematic diagram of yet another HARQ time sequenceaccording to an embodiment of the present invention;

FIG. 10 is a schematic diagram of another HARQ time sequence accordingto an embodiment of the present invention;

FIG. 11 is a schematic diagram of another HARQ time sequence accordingto an embodiment of the present invention;

FIG. 12 is a schematic diagram of yet another HARQ time sequenceaccording to an embodiment of the present invention;

FIG. 13 is a schematic diagram of a receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 14a is a schematic diagram of another receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 14b is a schematic diagram of another receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 14c is a schematic diagram of another receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 14d is a schematic diagram of another receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 14e is a schematic diagram of another receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 14f is a schematic diagram of another receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 14g is a schematic diagram of another receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 14h is a schematic diagram of another receiving status informationtransmission structure according to an embodiment of the presentinvention;

FIG. 15 is a block diagram of a terminal device according to anembodiment of the present invention; and

FIG. 16 is a block diagram of a network device according to anembodiment of the present invention.

To describe the technical solutions in the embodiments of the presentinvention more clearly, the following briefly describes the accompanyingdrawings required for describing the embodiments or the prior art. Aperson of ordinary skill in the art may still derive other drawings fromthese accompanying drawings without creative efforts.

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. The describedembodiments are merely a part rather than all of the embodiments of thepresent invention. All other embodiments obtained by a person ofordinary skill in the art based on the embodiments of the presentinvention without creative efforts shall fall within the protectionscope of the present invention.

Referring to FIG. 1, FIG. 1 is a schematic diagram of a wirelesscommunications network system according to an embodiment of the presentinvention. The wireless communications network system includes aterminal device 110 and a network device 120.

The terminal device 110 mentioned in this embodiment of the presentinvention may be a device that provides a user with voice and/or dataconnectivity, a handheld device with a wireless connection function, oranother processing device connected to a wireless modem. The terminaldevice may communicate with one or more core networks through a radioaccess network (RAN). The terminal device may be a mobile terminal, suchas a mobile phone (also referred to as a “cellular” phone) or a computerwith a mobile terminal, for example, may be a portable, a pocket-sized,a handheld, a computer built-in, or an in-vehicle mobile apparatus,which exchanges voice and/or data with the radio access network. Forexample, the terminal device may be a device such as a personalcommunications service (PCS) phone, a cordless telephone set, a SessionInitiation Protocol (SIP) phone, a wireless local loop (WLL) station, ora personal digital assistant (PDA). A terminal device may also bereferred to as a system, a subscriber unit, a subscriber station, amobile station, a remote station, an access point, a remote terminal, anaccess terminal, a user terminal, a user agent, a user device, or userequipment.

The network device 120 mentioned in this embodiment of the presentinvention may be a base station or an access point, or may be a devicein communication with a wireless terminal via one or more sectors at anair interface in an access network. The base station may be configuredto mutually convert a received over-the-air frame and an IP packet andserve as a router between the wireless terminal and a rest portion ofthe access network, and the rest portion of the access network mayinclude an Internet Protocol (IP) network. The base station may furthercoordinate attribute management of the air interface. For example, thebase station may be a base transceiver station (BTS) in GSM or CDMA, maybe a NodeB in WCDMA, or may be an evolved NodeB (eNB) in LTE. This isnot limited in the present invention.

The wireless communications system can be applied to 4.5G (the 4.5^(th)generation mobile communications), 5G (the 5^(th) generation mobilecommunications), and more advanced communications technologies.

Data sent by the terminal device 110 to the network device 120 isreferred to as uplink data; and data sent by the network device 120 tothe terminal device 110 is referred to as downlink data.

In this embodiment, an LTE-based wireless communications system is usedas an example for description. It should be noted that this embodimentof the present invention can be applied to any wireless communicationssystem in which data transmission is performed through scheduling, andis not limited to an LTE system.

In the LTE system, each radio frame consists of 10 subframes that are 1ms in length, and numbers of the subframes are 0 to 9. A subframe n−a isan a^(th) subframe previous to a subframe n, in other words, thesubframe n−a is the a^(th) subframe counted backward from the subframen. For example, if n=4 and a=2, the subframe n−a is a subframe 2 in aradio frame to which the subframe n belongs. For another example, if n=0and a=2, the subframe n−a is a subframe 8 in a radio frame previous to aradio frame to which the subframe n belongs. A subframe n+a is an a^(th)subframe next to the subframe n, in other words, the subframe n+a is thea^(th) subframe counted forward from the subframe n. For example, if n=4and a=3, the subframe n+a is a subframe 7 in a radio frame to which thesubframe n belongs. For another example, if n=8 and a=2, the subframen+a is a subframe 0 in a radio frame next to a radio frame to which thesubframe n belongs.

In the LTE system, each subframe includes 2 timeslots (also refer asslot), that is, each radio frame includes 20 timeslots, and numbers ofthe timeslots are 0 to 19. A timeslot n−a is an a^(th) timeslot previousto a timeslot n, in other words, the timeslot n−a is the a^(th) timeslotcounted backward from the timeslot n. For example, if n=4 and a=2, thetimeslot n−a is a timeslot 2 in a radio frame to which the timeslot nbelongs. For example, if n=0 and a=2, the timeslot n−a is a timeslot 18in a radio frame previous to a radio frame to which the timeslot nbelongs. A timeslot n+a is an a^(th) timeslot next to the timeslot n, inother words, the timeslot n+a is the a^(th) timeslot counted forwardfrom the timeslot n. For example, if n=4 and a=3, the timeslot n+4 is atimeslot 7 in a radio frame to which the timeslot n belongs. Forexample, if n=18 and a=2, the timeslot n+2 is a timeslot 0 in a radioframe next to a radio frame to which the timeslot n belongs.

For a normal cyclic prefix (normal CP), each subframe consists of 14symbols, that is, each subframe consists of symbols with sequencenumbers {#0, #1, #2, #3, #4, #5, #6, #7, #8, #9, #10, #11, #12, #13}.For an extended cyclic prefix (extended CP), each subframe consists of12 symbols, that is, each subframe consists of symbols with sequencenumbers {#0, #1, #2, #3, #4, #5, #6, #7, #8, #9, #10, #11}.

In this embodiment of the present invention, both an uplink symbol and adownlink symbol are referred to as a symbol for short. The uplink symbolis referred to as a single carrier frequency division multiple access(SC-FDMA) symbol. The downlink symbol is referred to as an orthogonalfrequency division multiplexing (OFDM) symbol. It should be noted that,if an uplink multiple access manner of orthogonal frequency divisionmultiple access (OFDMA) is introduced in a subsequent technology, theuplink symbol may also be referred to as an OFDM symbol. No limitationis imposed on an uplink multiple access manner and a downlink multipleaccess manner in the present disclosure.

In the LTE system, after receiving downlink data sent by the networkdevice 120, the terminal device 110 needs to send receiving statusinformation to the network device 120, so that the network device 120learns of a status of receiving the downlink data by the terminal device110. To meet a demand for a low-latency service, a short-TTI datatransmission mechanism is introduced, that is, a TTI of downlink data isshortened. In addition, to reduce a performance loss of the receivingstatus information, a TTI of the receiving status information iscontrolled to be greater than the TTI of the downlink data.

In an existing LTE system, a time domain resource occupied fortransmitting data whose TTI length is 1 ms is equal to or less than 1ms. For example, the first 1, 2, 3, or 4 symbols in a downlink subframeare used to transmit a PDCCH and other symbols in the subframe are usedto transmit downlink data. Therefore, a time domain resource occupiedfor transmitting downlink data whose TTI is 1 ms is less than 1 ms. Forexample, a last symbol in an uplink subframe is used to transmit asounding reference signal (SRS). Therefore, a time domain resourceactually occupied for transmitting uplink data whose TTI length is 1 msis less than 1 ms.

A short TTI is a TTI whose TTI length is less than 1 ms, such as, 0.5ms, a length of 4 symbols, a length of 3 symbols, a length of 2 symbols,or a length of 1 symbol. Similarly, a time domain resource occupied fortransmitting uplink data or downlink data whose TTI length is short maybe equal to or less than the short TTI length.

Referring to FIG. 2, FIG. 2 is a flowchart of a data transmission methodaccording to an embodiment of the present invention. The method isapplied to the wireless communications system shown in FIG. 1. As shownin FIG. 2, the method includes the following steps.

S110. A network device sends at least one piece of downlink data on afirst time domain resource.

Correspondingly, a terminal device receives, on the first time domainresource, the at least one piece of downlink data sent by the networkdevice.

The downlink data may be data carried on a physical downlink sharedchannel (PDSCH) or downlink semi-persistent scheduling (SPS) releasesignaling.

S120. A terminal device receives the at least one piece of downlink dataon the first time domain resource, and generates receiving statusinformation based on a receiving status of the received at least onepiece of downlink data.

After receiving the at least one piece of downlink data, the terminaldevice needs to determine whether the at least one piece of downlinkdata is correctly received, and then feeds back the receiving status,namely, a receiving result, to the network device. In this embodiment ofthe present invention, the receiving status information is used toindicate the receiving status of the at least one piece of downlinkdata. The receiving status information may also be referred to asHARQ-ACK feedback information, HARQ-ACK information for short. Thereceiving status information may be carried on a PUCCH or a PUSCH, thatis, the receiving status information is a type of uplink data that iscarried on the PUCCH or the PUSCH.

The HARQ-ACK information includes an ACK, a NACK, and/or discontinuoustransmission (DTX). The ACK indicates that the receiving is correct, theNACK indicates that the receiving is incorrect, and the DTX indicatesthat no downlink data is received. For example, when the downlink datais the data carried on the PDSCH, the receiving status information mayinclude the ACK and the NACK; or the receiving status information mayinclude the ACK, the NACK, and the DTX. The DTX indicates that nodownlink data is received. For example, when the downlink data is theSPS release signaling, and if the terminal device detects the SPSrelease signaling sent by the network device, the receiving statusinformation is the ACK; if the terminal device does not detect the SPSrelease signaling sent by the network device, the receiving statusinformation is the DTX. Optionally, when determining that the receivingstatus of the downlink data is the DTX, the terminal device may not sendthe receiving status information of the downlink data to the networkdevice.

Optionally, that the terminal device generates receiving statusinformation based on a receiving status of the received at least onepiece of downlink data includes: determining, by the terminal device,receiving statuses of all downlink data in the at least one piece ofdownlink data, and generates the receiving status information based onthe receiving statuses of all the downlink data.

Optionally, that the terminal device generates receiving statusinformation based on a receiving status of the received at least onepiece of downlink data includes: performing, by the terminal device, anAND logical operation on receiving statuses of all downlink data in thereceived at least one piece of downlink data, and then obtaining thereceiving status information. The receiving status information indicatesthat the receiving fails once one piece of the at least one piece ofdownlink data fails to be received; and the receiving status informationindicates that the receiving succeeds provided that all the downlinkdata is received successfully.

Optionally, that the terminal device generates receiving statusinformation based on a receiving status of the received at least onepiece of downlink data includes: generating, by the terminal device, thereceiving status information based on receiving statuses of all downlinkdata in the received at least one piece of downlink data, and selectinga PUCCH resource for carrying the receiving status information from aplurality of PUCCH resources, where the receiving status information andthe PUCCH resource jointly indicate the receiving status of the at leastone piece of downlink data.

Optionally, that the terminal device generates receiving statusinformation based on a receiving status of the received at least onepiece of downlink data includes: generating, by the terminal device, thereceiving status information based on receiving statuses of all downlinkdata in the received at least one piece of downlink data, where thegenerated receiving status information includes a plurality ofinformation fields, and information in different information fields isused to indicate receiving statuses of different downlink data in the atleast one piece of downlink data.

It should be noted that how the receiving status information isgenerated is not limited in the present disclosure, and the foregoingsolutions are optional solutions. In addition, how a receiving status ofdownlink data is determined is not limited in the present disclosureneither, and any manner in which whether downlink data is successfullyreceived by a receiver or not can be determined can be applied in thepresent disclosure.

S130. The terminal device sends the receiving status information on asecond time domain resource.

A transmission time interval of the receiving status information isgreater than a transmission time interval of any piece of downlink datain the at least one piece of downlink data, and the transmission timeinterval of the any piece of downlink data is less than 1 ms. Inaddition, a time interval between the second time domain resource andthe first time domain resource is less than 4 ms. A time length of thesecond time domain resource is equal to the transmission time intervalof the receiving status information. A time length of the first timedomain resource is greater than the transmission time interval of theany piece of downlink data. Therefore, the terminal device can receive,on the first time domain resource, the at least one piece of downlinkdata (in other words, one or more pieces of downlink data) sent by thenetwork device, and different downlink data in the at least one piece ofdownlink data is located in different symbols.

In the following two optional solutions, the time length of the secondtime domain resource is equal to the transmission time interval of thereceiving status information.

Optional solution 1: The receiving status information sent by theterminal device is carried on the PUCCH, and a time length of a timedomain resource occupied by the PUCCH and a PUCCH demodulation referencesignal (DMRS) together is equal to the time length of the second timedomain resource.

Optional solution 2: The receiving status information sent by theterminal device is carried on the PUCCH, and a time length of a timedomain resource occupied by the PUCCH is equal to the time length of thesecond time domain resource. That is, a time length of a time domainresource occupied by the PUCCH and a PUCCH DMRS together is greater thanthe time length of the second time domain resource. The PUCCH DMRS isprevious to the PUCCH. For example, when the time length of the secondtime domain resource is 2 symbols, the PUCCH occupies 2 symbols, and thePUCCH DMRS occupies 1 or 2 symbols, the PUCCH and the PUCCH DMRS occupy3 or 4 symbols together, greater than the time length of the second timedomain resource. In this case, the PUCCH DMRS of the terminal device(referred to as a first terminal device) may overlap with a PUCCH of asecond terminal device in a time domain, and then code division isperformed (for example, by using different cyclic shifts or orthogonalspreading code). Similarly, the PUCCH of the terminal device may overlapwith a PUCCH DMRS of a third terminal device in the time domain, andthen code division is performed. The first terminal device, the secondterminal device, and the third terminal device are different terminaldevices.

To reduce a latency, not only a TTI length needs to be shortened, butalso a time interval between a receiving time of downlink data and asending time of HARQ-ACK feedback information needs to be reduced. In anexisting frequency division duplexing (FDD) system, the time intervalbetween a receiving time of downlink data and a sending time of HARQ-ACKfeedback information is 4 ms. For example, a TTI length ofuplink/downlink data may be shortened to a length of 0.5 ms, 4 symbols,3 symbols, 2 symbols, or 1 symbol. However, performance for receivinguplink data is affected after a TTI of the uplink data is shortened.

To enhance performance for receiving the receiving status information(namely, uplink data), a TTI length of the receiving status informationis set to greater than a TTI length of downlink data. For example, theTTI length of the receiving status information is 0.5 ms or 1 ms, andthe TTI length of downlink data may be 1, 2, 3, or 4 symbols. Forexample, the TTI length of the receiving status information is 3 or 4symbols, and the TTI length of downlink data is 1 or 2 symbols. Foranother example, the TTI length of the receiving status information is 1ms, and the TTI length of downlink data is 0.5 ms.

A prior-art hybrid automatic repeat request (HARQ) time sequence cannotmeet a demand for inequality between the TTI length of the uplinkreceiving status information and the TTI length of downlink data.Therefore, the HARQ time sequence needs to be redefined. The HARQ timesequence is a transmission time sequence between downlink data andreceiving status information (namely, HARQ-ACK feedback information).The HARQ time sequence is redefined, so that the time interval between areceiving time of downlink data and a sending time of HARQ-ACK feedbackinformation is less than 4 ms.

S140. The network device receives the receiving status information onthe second time domain resource.

Specifically, the network device receives, on the second time domainresource, the receiving status information sent by the terminal device.

Optionally, the flowchart of the data transmission method shown in FIG.2 may further include the following steps after step S140.

S150. If the receiving status information indicates that one or morepieces of downlink data in the at least one piece of downlink data failto be received, the network device retransmits the one or more pieces ofdownlink data on a third time domain resource. A time interval betweenthe third time domain resource and the first time domain resource isless than 8 ms.

The time interval between the third time domain resource and the firsttime domain resource is a HARQ round-trip time (RTT). The HARQ RTT is aminimum time interval between a retransmitted data packet and aninitially transmitted data packet. In the existing FDD system, theminimum time interval between a retransmitted data packet and aninitially transmitted data packet is 8 ms. The latency can be furtherreduced by shortening the HARQ RTT.

S160. The terminal device receives the retransmitted one or more piecesof downlink data on the third time domain resource.

Specifically, if the terminal device fails to receive the one or morepieces of downlink data in the at least one piece of downlink data onthe first time domain resource, the terminal device receives, on thethird time domain resource, the one or more pieces of downlink data thatare retransmitted by the network device.

It should be noted that step S120 and step S130 in this embodiment maybe applied to a terminal device, that is, step S120 and step S130 areused as an invention embodiment of a terminal device side and are notlimited by an operation of a network device side. In this way, thisembodiment may include the following steps:

S120. The terminal device receives at least one piece of downlink dataon a first time domain resource.

S130. The terminal device sends receiving status information on a secondtime domain resource.

Optionally, step S160 may further be included. If the terminal devicefails to receive one or more pieces of downlink data in the at least onepiece of downlink data on the first time domain resource, the terminaldevice receives the retransmitted one or more pieces of downlink data ona third time domain resource.

Similarly, step S110 and step S140 in this embodiment may be applied toa network device, that is, step S110 and step S140 are used as aninvention embodiment of a network device side and are not limited by anoperation of a terminal device side. In this way, this embodiment mayinclude the following steps:

S110. The network device sends at least one piece of downlink data on afirst time domain resource.

S140. The network device receives receiving status information on asecond time domain resource.

Optionally, step S150 may further be included. If the receiving statusinformation indicates that one or more pieces of downlink data in the atleast one piece of downlink data fail to be received, the network deviceretransmits the one or more pieces of downlink data on a third timedomain resource.

According to the data transmission method provided in this embodiment,the terminal device receives the at least one piece of downlink data onthe first time domain resource; and then sends the receiving statusinformation on the second time domain resource. The time intervalbetween the second time domain resource and the first time domainresource is less than 4 ms, the transmission time interval of the anypiece of downlink data is less than the transmission time interval ofthe receiving status information, and the transmission interval of theany piece of downlink data is less than 1 ms. According to the datatransmission method, a transmission time interval of downlink data and atime interval between a sending time of the receiving status informationand a receiving time of the at least one piece of downlink data areshortened, thereby reducing a latency. In addition, the transmissiontime interval of the receiving status information (namely, uplink data)is greater than the transmission time interval of downlink data. Thisenhances performance for receiving the receiving status information, andincreases a probability that the network device correctly receives thereceiving status information returned by the terminal device. Inaddition, according to the data transmission method, on a premise thatthe TTI of downlink data and the time interval between a receiving timeof the at least one piece of downlink data and a sending time of thereceiving status information are shortened, the HARQ RTT is reduced, andthe latency is further reduced effectively.

A HARQ time sequence is described in detail in the following embodimentscorresponding to FIG. 3 to FIG. 12.

Optionally, before sending at least one piece of downlink data to aterminal device on a first time domain resource, a network device sendssignaling to the terminal device. Correspondingly, before receiving theat least one piece of downlink data on the first time domain resource,the terminal device receives the signaling sent by the network device.The signaling is used to indicate a time interval between a second timedomain resource and a first time domain resource, and/or a time intervalbetween a second time domain resource and a third time domain resource,and/or a time interval between a third time domain resource and a firsttime domain resource.

Referring to FIG. 3, FIG. 3 is a schematic diagram of a HARQ timesequence according to an embodiment of the present invention. In thisembodiment, a TTI length of receiving status information is 0.5 ms(namely, one timeslot), and a TTI length of any piece of downlink datain at least one piece of downlink data is 4 symbols or 3 symbols.

A first time domain resource is a timeslot n−2 (as shown in FIG. 3) or atimeslot n−3, and a second time domain resource is a timeslot n. Thetimeslot n−2 is a second timeslot previous to the timeslot n, and thetimeslot n−3 is a third timeslot previous to the timeslot n.

A timeslot includes 7 or 6 symbols and the TTI length of the any pieceof downlink data is 4 symbols or 3 symbols. Therefore, the first timedomain resource can accommodate two pieces of downlink data at most. Forexample, the at least one piece of downlink data includes one piece ofdownlink data whose TTI length is 4 symbols and/or one piece of downlinkdata whose TTI length is 3 symbols. For example, the at least one pieceof downlink data includes one or two pieces of downlink data whose TTIis 3 symbols.

A network device sends the at least one piece of downlink data to aterminal device in the timeslot n−2 or the timeslot n−3;correspondingly, the terminal device receives, in the timeslot n−2 orthe timeslot n−3, the at least one piece of downlink data sent by thenetwork device. Then, the terminal device sends the receiving statusinformation to the network device in the timeslot n; correspondingly,the network device receives, in the timeslot n, the receiving statusinformation sent by the terminal device.

In this embodiment, if the first time domain resource is the timeslotn−2, a time interval between a receiving time of the downlink data (thetimeslot n−2) and a sending time of the receiving status information(the timeslot n) (namely, a time interval between the first time domainresource and the second time domain resource) is less than or equal to 1ms (a length of 2 timeslots). If the first time domain resource is thetimeslot n−3, a time interval between a receiving time of the downlinkdata (the timeslot n−3) and a sending time of the receiving statusinformation (the timeslot n) is less than or equal to 1.5 ms (a lengthof 3 timeslots). Therefore, after this embodiment is used, the timeinterval between a receiving time of the downlink data and a sendingtime of the receiving status information is far less than a timeinterval (4 ms) between a receiving time of downlink data and a sendingtime of receiving status information in an existing FDD system. In thisway, a latency is effectively reduced.

Further, if the receiving status information indicates that one or morepieces of downlink data in the at least one piece of downlink datareceived by the terminal device fail to be received (are receivedincorrectly or not received), the network device may retransmit, in atimeslot n+2 or a timeslot n+3, the one or more pieces of downlink datathat fail to be received. That is, a third time domain resource is thetimeslot n+2 or the timeslot n+3.

Correspondingly, if the one or more pieces of downlink data in the atleast one piece of downlink data received by the terminal device on thefirst time domain resource fail to be received, the terminal device mayreceive, in the timeslot n+2 or the timeslot n+3, the one or more piecesof downlink data that are retransmitted by the network device.

It can be learned that, if the first time domain resource is thetimeslot n−2, a HARQ RTT is not greater than 2 ms or 2.5 ms (a length of4 or 5 timeslots), far less than 8 ms in the existing FDD system. If thefirst time domain resource is the timeslot n−3, a HARQ RTT is notgreater than 2.5 ms or 3 ms, less than existing 8 ms.

The HARQ time sequence provided in this embodiment not only can meet atime sequence requirement on inequality between the TTI length of thereceiving status information and the TTI length of downlink data, butalso reduces the time interval between a time at which the terminaldevice receives the downlink data and a time at which the terminaldevice sends the receiving status information, thereby reducing thelatency. In addition, the HARQ RTT is reduced; therefore, the latency isfurther reduced effectively.

Referring to FIG. 4, FIG. 4 is a schematic diagram of another HARQ timesequence according to an embodiment of the present invention. In thisembodiment, a TTI length of receiving status information is 0.5 ms, anda TTI length of any piece of downlink data in at least one piece ofdownlink data is a length of 4 symbols or 3 symbols. A first time domainresource is the last 3 symbols or 4 symbols of a timeslot n−3 and thefirst 4 symbols or 3 symbols of a timeslot n−2, and a second time domainresource is a timeslot n.

It can be learned from FIG. 4 that a time interval between a receivingtime of the downlink data and a sending time of the receiving statusinformation is less than 1.5 ms (a length of 3 timeslots), far less than4 ms in an existing FDD system. Therefore, a latency is effectivelyreduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by a terminal device on the first timedomain resource fail to be received, the terminal device sends, on thesecond time domain resource to a network device, the receiving statusinformation indicating that the one or more pieces of downlink data failto be received. After receiving the receiving status information, thenetwork device retransmits the one or more pieces of downlink data on athird time domain resource. Correspondingly, the terminal devicereceives the retransmitted one or more pieces of downlink data on thethird time domain resource. The third time domain resource is the last 3symbols or 4 symbols of a timeslot n+2 and the first 4 symbols or 3symbols of a timeslot n+3, or the third time domain resource is atimeslot n+2 or a timeslot n+3. It can be learned that a HARQ RTT inthis embodiment is not greater than 3 ms (a length of 6 timeslots), farless than 8 ms in the existing FDD system. Therefore, the latency iseffectively reduced.

Referring to FIG. 5, FIG. 5 is a schematic diagram of another HARQ timesequence according to an embodiment of the present invention. In thisembodiment, a TTI length of receiving status information is 0.5 ms, anda TTI length of any piece of downlink data in at least one piece ofdownlink data is 2 symbols or 1 symbol. A first time domain resource isa timeslot n−2, and a second time domain resource is a timeslot n.

Optionally, if a TTI length of one piece of downlink data is 2 symbolsand the downlink data is located in a last symbol of the timeslot n−2and a first symbol of a timeslot n−1, the downlink data may also beconsidered as downlink data received by a terminal device in thetimeslot n−2.

Correspondingly, a network device sends the at least one piece ofdownlink data in the timeslot n−2, and the terminal device receives, inthe timeslot n−2, the at least one piece of downlink data sent by thenetwork device. Then, the terminal device sends the receiving statusinformation to the network device in the timeslot n, and the networkdevice receives, in the timeslot n, the receiving status informationsent by the terminal device.

In this embodiment, a time interval between a receiving time of thedownlink data and a sending time of the receiving status information isless than or equal to 1 ms (a length of 2 timeslots), far less than 4 msin an existing FDD system. Therefore, a latency is effectively reduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by the terminal device on the first timedomain resource fail to be received, and the TTI length of the any pieceof downlink data is a length of 1 symbol, the terminal device mayreceive, after 4 symbols, 0.5 ms, 1 ms, or 1.5 ms after the receivingstatus information is sent, the one or more pieces of downlink data thatare retransmitted by the network device. Correspondingly, if thereceiving status information indicates that one or more pieces ofdownlink data fail to be received, and the TTI length of the any pieceof downlink data is a length of 1 symbol, the network device mayretransmit the one or more pieces of downlink data after 4 symbols, 0.5ms, 1 ms, or 1.5 ms after the receiving status information is received.It can be learned that a HARQ RTT is not greater than 2.5 ms (a lengthof 5 timeslots), far less than 8 ms in the existing FDD system.Therefore, the latency is effectively reduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by the terminal device on the first timedomain resource fail to be received, and the TTI length of the any pieceof downlink data is a length of 2 symbols, the terminal device mayreceive, after 8 symbols, 1 ms, or 1.5 ms after the receiving statusinformation is sent, the one or more pieces of downlink data that areretransmitted by the network device. Correspondingly, if the receivingstatus information indicates that one or more pieces of downlink datafail to be received, and the TTI length of the any piece of downlinkdata is a length of 2 symbols, the network device may retransmit the oneor more pieces of downlink data after 8 symbols, 1 ms, or 1.5 ms afterthe receiving status information is received. It can be learned that aHARQ RTT is not greater than 2.5 ms (a length of 5 timeslots), far lessthan 8 ms in the existing FDD system. Therefore, the latency iseffectively reduced.

Referring to FIG. 6, FIG. 6 is a schematic diagram of another HARQ timesequence according to an embodiment of the present invention. In thisembodiment, a TTI length of receiving status information is 0.5 ms, anda TTI length of any piece of downlink data in at least one piece ofdownlink data is 1 symbol. A first time domain resource is the last 3symbols of a timeslot n−2 and the first 4 or 3 symbols of a timeslotn−1, and a second time domain resource is a timeslot n. It can belearned that a time interval between a receiving time of the downlinkdata and a sending time of the receiving status information is less than1 ms (a length of 2 timeslots), far less than 4 ms in an existing FDDsystem. Therefore, a latency can be effectively reduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by a terminal device on the first timedomain resource fail to be received, the terminal device sends, on thesecond time domain resource to a network device, the receiving statusinformation used to indicate that the one or more pieces of downlinkdata fail to be received. Correspondingly, the network device mayretransmit the one or more pieces of downlink data after 4 symbols, 0.5ms, 1 ms, or 1.5 ms after the receiving status information is received.That is, the terminal device may receive, after 4 symbols, 0.5 ms, 1 ms,or 1.5 ms after the receiving status information is sent, the one ormore pieces of downlink data that are retransmitted by the networkdevice. It can be learned that a HARQ RTT is not greater than 2.5 ms,far less than 8 ms in the existing FDD system. Therefore, the latency iseffectively reduced.

Referring to FIG. 7, FIG. 7 is a schematic diagram of still another HARQtime sequence according to an embodiment of the present invention. Inthis embodiment, a TTI length of receiving status information is 1 ms,and a TTI length of any piece of downlink data in at least one piece ofdownlink data is 0.5 ms. A first time domain resource is a subframe n−2(as shown in FIG. 7) or a subframe n−3, and a second time domainresource is a subframe n.

If the first time domain resource is the subframe n−2, a time intervalbetween a receiving time of the downlink data and a sending time of thereceiving status information (the subframe n) is less than 2 ms; if thefirst time domain resource is the subframe n−3, a time interval betweena receiving time of the downlink data and a sending time of thereceiving status information (the subframe n) is less than 3 ms. In thetwo scenarios, the time interval between a receiving time of thedownlink data and a sending time of the receiving status information isless than 4 ms in an existing FDD system. Therefore, a latency can beeffectively reduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by a terminal device on the first timedomain resource fail to be received, the terminal device sends, on thesecond time domain resource, the receiving status information indicatingthat the one or more pieces of downlink data fail to be received. Afterreceiving the receiving status information, a network device mayretransmit the one or more pieces of downlink data in a subframe n+2 ora subframe n+3. That is, the terminal device may receive the one or morepieces of downlink data in the subframe n+2 or the subframe n+3. It canbe learned that a HARQ RTT is not greater than 4 ms, 5 ms, or 6 ms, lessthan 8 ms in the existing FDD system. Therefore, the latency is furtherreduced.

In another application scenario of this embodiment, a TTI length ofreceiving status information is 1 ms, and a TTI length of any piece ofdownlink data is 4, 3, 2, or 1 symbol. A first time domain resource is asubframe n−2, and a second time domain resource is a subframe n. It canbe learned that a time interval between a receiving time of the downlinkdata and a sending time of the receiving status information is less thanor equal to 2 ms, less than 4 ms in an existing FDD system. Therefore, alatency can be effectively reduced.

Further, if a terminal device fails to receive one or more pieces ofdownlink data in the at least one piece of downlink data on the firsttime domain resource, the terminal device may receive, on a third timedomain resource, the one or more pieces of downlink data that areretransmitted by a network device. The third time domain resource may bea subframe n+2. It can be learned that a HARQ RTT is less than or equalto 4 ms, far less than 8 ms in the existing FDD system. Therefore, thelatency is further reduced.

Referring to FIG. 8, FIG. 8 is a schematic diagram of still another HARQtime sequence according to an embodiment of the present invention. Inthis embodiment, a TTI length of receiving status information is 1 ms,and a TTI length of any piece of downlink data in at least one piece ofdownlink data is 0.5 ms. A first time domain resource is a secondtimeslot of a subframe n−3 and a first timeslot of a subframe n−2, and asecond time domain resource is a subframe n. It can be learned that atime interval between a receiving time of the downlink data and asending time of the receiving status information is less than 3 ms, lessthan 4 ms in an existing FDD system. Therefore, a latency can beeffectively reduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by a terminal device on the first timedomain resource fail to be received, after the receiving statusinformation indicating that the one or more pieces of downlink data failto be received is sent on the second time domain resource, a networkdevice may retransmit the one or more pieces of downlink data in asecond timeslot of a subframe n+2 and a first timeslot of a subframen+3, or a subframe n+2, or a subframe n+3. That is, the terminal devicemay receive, in the second timeslot of the subframe n+2 and the firsttimeslot of the subframe n+3, or the subframe n+2, or the subframe n+3,the one or more pieces of downlink data that are retransmitted by thenetwork device. It can be learned that a HARQ RTT is less than 6 ms or 5ms, less than 8 ms in the existing FDD system. Therefore, the latency isfurther reduced.

Referring to FIG. 9, FIG. 9 is a schematic diagram of yet another HARQtime sequence according to an embodiment of the present invention. Inthis embodiment, a TTI length of receiving status information is 1 ms,and a TTI length of any piece of downlink data in at least one piece ofdownlink data is 3 symbols or 4 symbols. A first time domain resource isthe last 10 symbols or 9 symbols of a subframe n−2 and the first 4symbols or 3 symbols of a subframe n−1, and a second time domainresource is a subframe n. It can be learned that a time interval betweena receiving time of the downlink data and a sending time of thereceiving status information is less than 2 ms, less than 4 ms in anexisting FDD system. Therefore, a latency is effectively reduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by a terminal device on the first timedomain resource fail to be received, and the receiving statusinformation indicating that the one or more pieces of downlink data failto be received is sent on the second time domain resource, afterreceiving the receiving status information, a network device retransmitsthe one or more pieces of downlink data in a subframe n+2. That is, theterminal device may receive, in the subframe n+2, the one or more piecesof downlink data that are retransmitted by the network device. It can belearned that a HARQ RTT is less than 4 ms, far less than 8 ms in theexisting FDD system. Therefore, the latency is further reduced.

Referring to FIG. 10, FIG. 10 is a schematic diagram of another HARQtime sequence according to an embodiment of the present invention. Inthis embodiment, a TTI length of receiving status information is 1 ms,and a TTI length of any piece of downlink data in at least one piece ofdownlink data is 2 symbols. A first time domain resource is the last 6symbols of a subframe n−2 and the first 8 or 6 symbols of a subframen−1, or a first time domain resource is a second timeslot of a subframen−2 and a first timeslot of a subframe n−1, or a first time domainresource is the last 8 symbols of a subframe n−2 and the first 6 or 4symbols of a subframe n−1. A second time domain resource is a subframen. It can be learned that a time interval between a receiving time ofthe downlink data and a sending time of the receiving status informationis less than 2 ms, less than 4 ms in an existing FDD system. Therefore,a latency is effectively reduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by a terminal device on the first timedomain resource fail to be received, and the receiving statusinformation indicating that the one or more pieces of downlink data failto be received is sent on the second time domain resource, a networkdevice may retransmit the one or more pieces of downlink data in asubframe n+2. That is, the terminal device may receive, in the subframen+2, the one or more pieces of downlink data that are retransmitted bythe network device. It can be learned that a HARQ RTT is less than 4 ms,far less than 8 ms in the existing FDD system. Therefore, the latency isfurther reduced.

Referring to FIG. 11, FIG. 11 is a schematic diagram of another HARQtime sequence according to an embodiment of the present invention. Inthis embodiment, a TTI length of receiving status information is 1 ms,and a TTI length of any piece of downlink data in at least one piece ofdownlink data is 1 symbol. A first time domain resource may be the last3 symbols of a subframe n−2 and the first 11 or 9 symbols of a subframen−1, or a first time domain resource may be a second timeslot of asubframe n−2 and a first timeslot of a subframe n−1. A second timedomain resource is a subframe n. It can be learned that a time intervalbetween a receiving time of the downlink data and a sending time of thereceiving status information is less than 2 ms. Therefore, a latency canbe effectively reduced.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by a terminal device on the first timedomain resource fail to be received, and the receiving statusinformation indicating that the one or more pieces of downlink data failto be received is sent on the second time domain resource, a networkdevice may retransmit the one or more pieces of downlink data in asubframe n+2. That is, the terminal device may receive, in the subframen+2, the one or more pieces of downlink data that are retransmitted bythe network device. It can be learned that a HARQ RTT is less than 4 ms,far less than 8 ms in an existing FDD system. Therefore, the latency isfurther reduced.

Referring to FIG. 12, FIG. 12 is a schematic diagram of yet another HARQtime sequence according to an embodiment of the present invention. Inthis embodiment, a TTI length of receiving status information is alength of 4 symbols or 3 symbols, and a TTI length of any piece ofdownlink data is a length of 1 symbol or 2 symbols. A first time domainresource is a symbol set in a subframe n−1, and a second time domainresource is a symbol set in a subframe n. It can be learned that a timeinterval between the second time domain resource and the first timedomain resource is less than or equal to 1 ms, less than 4 ms in anexisting FDD system. Therefore, a latency is effectively reduced.

Optionally, the first time domain resource may be an i^(th) downlinksymbol set in the subframe n−1, the second time domain resource may bean i^(th) uplink symbol set in the subframe n, and i is 1, 2, 3, or 4.

Optionally, the first time domain resource may be a second downlinksymbol set in the subframe n−1, and the second time domain resource maybe a first uplink symbol set in the subframe n; the first time domainresource may be a third downlink symbol set in the subframe n−1, and thesecond time domain resource may be a second uplink symbol set in thesubframe n; the first time domain resource may be a fourth downlinksymbol set in the subframe n−1, and the second time domain resource maybe a third uplink symbol set in the subframe n; or the first time domainresource may be a first downlink symbol set in the subframe n, and thesecond time domain resource may be a fourth uplink symbol set in thesubframe n.

For ease of description, a concept of a symbol set is introduced in thisembodiment. A normal CP subframe is used as an example to describe thefirst eight types of the following symbol set structures. The normal CPsubframe includes symbols with sequence numbers {#0, #1, #2, #3, #4, #5,#6, #7, #8, #9, #10, #11, #12, #13}. An extended CP is used as anexample to describe a structure 9 and a structure 10, and an extended CPsubframe includes symbols with sequence numbers {#0, #1, #2, #3, #4, #5,#6, #7, #8, #9, #10, #11}.

One downlink subframe includes 4 downlink symbol sets and isspecifically divided into a first downlink symbol set, a second downlinksymbol set, a third downlink symbol set, and a fourth downlink symbolset based on a downlink structure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. Oneuplink subframe includes 4 uplink symbol sets and is specificallydivided into a first uplink symbol set, a second uplink symbol set, athird uplink symbol set, and a fourth uplink symbol set based on thefollowing uplink subframe symbol set structure 1, 2, 3, 4, 9, or 10.

When the receiving status information is transmitted on a symbol set, aTTI of the receiving status information is all symbols included in thesymbol set. For example, if a symbol set for transmitting the receivingstatus information includes 4 symbols, the TTI of the receiving statusinformation is in a length of 4 symbols; if a symbol set fortransmitting the receiving status information includes 3 symbols, theTTI of the receiving status information is in a length of 3 symbols.

Uplink/downlink subframe symbol set structure 1: a first uplink/downlinksymbol set includes symbols with sequence numbers {#0, #1, #2, #3}, asecond uplink/downlink symbol set includes symbols with sequence numbers{#4, #5, #6}, a third uplink/downlink symbol set includes symbols withsequence numbers {#7, #8, #9, #10}, and a fourth uplink/downlink symbolset includes symbols with sequence numbers {#11, #12, #13}.

Uplink/downlink subframe symbol set structure 2: a first uplink/downlinksymbol set includes symbols with sequence numbers {#0, #1, #2}, a seconduplink/downlink symbol set includes symbols with sequence numbers {#3,#4, #5, #6}, a third uplink/downlink symbol set includes symbols withsequence numbers {#7, #8, #9}, and a fourth uplink/downlink symbol setincludes symbols with sequence numbers {#10, #11, #12, #13}.

Uplink/downlink subframe symbol set structure 3: a first uplink/downlinksymbol set includes symbols with sequence numbers {#0, #1, #2, #3}, asecond uplink/downlink symbol set includes symbols with sequence numbers{#4, #5, #6}, a third uplink/downlink symbol set includes symbols withsequence numbers {#7, #8, #9}, and a fourth uplink/downlink symbol setincludes symbols with sequence numbers {#10, #11, #12, #13}.

Uplink/downlink subframe symbol set structure 4: a first uplink/downlinksymbol set includes symbols with sequence numbers {#0, #1, #2}, a seconduplink/downlink symbol set includes symbols with sequence numbers {#3,#4, #5, #6}, a third uplink/downlink symbol set includes symbols withsequence numbers {#7, #8, #9, #10}, and a fourth uplink/downlink symbolset includes symbols with sequence numbers {#11, #12, #13}.

Downlink subframe symbol set structure 5: a first downlink symbol setincludes symbols with sequence numbers {#0, #1, #2, #3}, a seconddownlink symbol set includes symbols with sequence numbers {#4, #5, #6,#7}, a third downlink symbol set includes symbols with sequence numbers{#8, #9, #10, #11}, and a fourth downlink symbol set includes symbolswith sequence numbers {#12, #13}.

Downlink subframe symbol set structure 6: a first downlink symbol setincludes symbols with sequence numbers {#0, #1, #2, #3}, a seconddownlink symbol set includes symbols with sequence numbers {#4, #5, #6,#7}, a third downlink symbol set includes symbols with sequence numbers{#8, #9}, and a fourth downlink symbol set includes symbols withsequence numbers {#10, #11, #12, #13}.

Downlink subframe symbol set structure 7: a first downlink symbol setincludes symbols with sequence numbers {#0, #1, #2, #3}, a seconddownlink symbol set includes symbols with sequence numbers {#4, #5}, athird downlink symbol set includes symbols with sequence numbers {#6,#7, #8, #9}, and a fourth downlink symbol set includes symbols withsequence numbers {#10, #11, #12, #13}.

Downlink subframe symbol set structure 8: a first downlink symbol setincludes symbols with sequence numbers {#0, #1}, a second downlinksymbol set includes symbols with sequence numbers {#2, #3, #4, #5}, athird downlink symbol set includes symbols with sequence numbers {#6,#7, #8, #9}, and a fourth downlink symbol set includes symbols withsequence numbers {#10, #11, #12, #13}.

Uplink/downlink subframe symbol set structure 9: a first uplink/downlinksymbol set includes symbols with sequence numbers {#0, #1, #2}, a seconduplink/downlink symbol set includes symbols with sequence numbers {#3,#4, #5}, a third uplink/downlink symbol set includes symbols withsequence numbers {#6, #7, #8}, and a fourth uplink/downlink symbol setincludes symbols with sequence numbers {#9, #10, #11}.

Uplink/downlink subframe symbol set structure 10: a firstuplink/downlink symbol set includes symbols with sequence numbers {#0,#1, #2, #3}, a second uplink/downlink symbol set includes symbols withsequence numbers {#4, #5}, a third uplink/downlink symbol set includessymbols with sequence numbers {#6, #7, #8, #9}, and a fourthuplink/downlink symbol set includes symbols with sequence numbers {#10,#11}.

Further, if one or more pieces of downlink data in at least one piece ofdownlink data received by a terminal device on the first time domainresource fail to be received, and after the receiving status informationindicating that the one or more pieces of downlink data fail to bereceived is sent on the second time domain resource, a network devicemay retransmit the one or more pieces of downlink data on a third timedomain resource. That is, the terminal device may receive, on the thirdtime domain resource, the one or more pieces of downlink data that areretransmitted by the network device.

Optionally, the third time domain resource may be an i^(th) downlinksymbol set in a subframe n+1, and i is 1, 2, 3, or 4.

Optionally, if the second time domain resource may be the first uplinksymbol set in the subframe n, the third time domain resource may be afourth downlink symbol set in the subframe n+1; if the second timedomain resource is the second uplink symbol set in the subframe n, thethird time domain resource is a first downlink symbol set in thesubframe n+1; if the second time domain resource is the third uplinksymbol set in the subframe n, the third time domain resource is a seconddownlink symbol set in the subframe n+1; or if the second time domainresource is the fourth uplink symbol set in the subframe n, the thirdtime domain resource is a third downlink symbol set in the subframe n+1.It can be learned that a HARQ RTT is less than or equal to 2 ms.Therefore, a latency is effectively reduced.

In still another embodiment of the present invention, a TTI length ofreceiving status information is a length of 2 symbols, and a TTI lengthof any piece of downlink data in at least one piece of downlink data isa length of 1 symbol. A time interval between a second time domainresource and a first time domain resource is less than 1 ms. It can belearned that the time interval is less than 4 ms in an existing FDDsystem. Therefore, a latency is effectively reduced.

For ease of description, a concept of a symbol set is also introduced.One normal CP subframe includes 7 symbol sets, every two symbols formone symbol set, and the 7 symbol sets are a first symbol set, a secondsymbol set, a third symbol set, a fourth symbol set, a fifth symbol set,a sixth symbol set, and a seventh symbol set.

Optionally, the first time domain resource may be a fifth symbol set ina subframe n−1, and the second time domain resource may be a firstsymbol set in a subframe n; the first time domain resource may be asixth symbol set in a subframe n−1, and the second time domain resourcemay be a second symbol set in a subframe n; the first time domainresource may be a seventh symbol set in a subframe n−1, and the secondtime domain resource may be a third symbol set in a subframe n; thefirst time domain resource may be a first symbol set in a subframe n,and the second time domain resource may be a fourth symbol set in thesubframe n; the first time domain resource may be a second symbol set ina subframe n, and the second time domain resource may be a fifth symbolset in the subframe n; the first time domain resource may be a thirdsymbol set in a subframe n, and the second time domain resource may be asixth symbol set in the subframe n; or the first time domain resourcemay be a fourth symbol set in a subframe n, and the second time domainresource may be a seventh symbol set in the subframe n.

Optionally, the first time domain resource may be a fourth symbol set ina subframe n−1, and the second time domain resource may be a firstsymbol set in a subframe n; the first time domain resource may be afifth symbol set in a subframe n−1, and the second time domain resourcemay be a second symbol set in a subframe n; the first time domainresource may be a sixth symbol set in a subframe n−1, and the secondtime domain resource may be a third symbol set in a subframe n; thefirst time domain resource may be a seventh symbol set in a subframen−1, and the second time domain resource may be a fourth symbol set in asubframe n; the first time domain resource may be a first symbol set ina subframe n, and the second time domain resource may be a fifth symbolset in the subframe n; the first time domain resource may be a secondsymbol set in a subframe n, and the second time domain resource may be asixth symbol set in the subframe n; or the first time domain resourcemay be a third symbol set in a subframe n, and the second time domainresource may be a seventh symbol set in the subframe n.

Optionally, the first time domain resource is a symbol j−6 and a symbolj−5, the first time domain resource is a symbol j−8 and a symbol j−7, orthe first time domain resource is a symbol j−5 and a symbol j−4. Thesecond time domain resource is a symbol j and a symbol j+1. The symbolj−4 is a fourth symbol counted backward from a symbol j; the symbol j−5is a fifth symbol counted backward from the symbol j; the symbol j−6 isa sixth symbol counted backward from the symbol j; the symbol j−7 is aseventh symbol counted backward from the symbol j; and the symbol j−8 isan eighth symbol counted backward from the symbol j. The symbol j+1 is afirst symbol counted forward from the symbol j. For example, if j=0,that is, if the symbol j is a symbol with a sequence number #0, thesymbol j−4 is a symbol, with a sequence number #11, in a subframeprevious to a subframe to which the symbol j belongs, and so on. Variouscases are not described one by one by using examples herein.

Further, if one or more pieces of downlink data in the at least onepiece of downlink data received by a terminal device on the first timedomain resource fail to be received, and the receiving statusinformation indicating that the one or more pieces of downlink data failto be received is sent on the second time domain resource, a networkdevice may retransmit the one or more pieces of downlink data on a thirdtime domain resource. That is, the terminal device may receive, on thethird time domain resource, the one or more pieces of downlink data thatare retransmitted by the network device. A time interval between thethird time domain resource and the first time domain resource is lessthan 8 ms.

Optionally, the second time domain resource may be the first symbol setin the subframe n, and the third time domain resource may be the fourthsymbol set in the subframe n; the second time domain resource may be thesecond symbol set in the subframe n, and the third time domain resourcemay be the fifth symbol set in the subframe n; the second time domainresource may be the third symbol set in the subframe n, and the thirdtime domain resource may be the sixth symbol set in the subframe n; thesecond time domain resource may be the fourth symbol set in the subframen, and the third time domain resource may be the seventh symbol set inthe subframe n; the second time domain resource may be the fifth symbolset in the subframe n, and the third time domain resource may be a firstsymbol set in a subframe n+1; the second time domain resource may be thesixth symbol set in the subframe n, and the third time domain resourcemay be a second symbol set in a subframe n+1; or the second time domainresource may be the seventh symbol set in the subframe n, and the thirdtime domain resource may be a third symbol set in a subframe n+1.

Optionally, the second time domain resource may be the first symbol setin the subframe n, and the third time domain resource may be the fifthsymbol set in the subframe n; the second time domain resource may be thesecond symbol set in the subframe n, and the third time domain resourcemay be the sixth symbol set in the subframe n; the second time domainresource may be the third symbol set in the subframe n, and the thirdtime domain resource may be the seventh symbol set in the subframe n;the second time domain resource may be the fourth symbol set in thesubframe n, and the third time domain resource may be a first symbol setin a subframe n+1; the second time domain resource may be the fifthsymbol set in the subframe n, and the third time domain resource may bea second symbol set in a subframe n+1; the second time domain resourcemay be the sixth symbol set in the subframe n, and the third time domainresource may be a third symbol set in a subframe n+1; or the second timedomain resource may be the seventh symbol set in the subframe n, and thethird time domain resource may be a fourth symbol set in a subframe n+1.

Optionally, the second time domain resource is the symbol j and thesymbol j+1; and the third time domain resource is a symbol j+6 and asymbol j+7, a symbol j+8 and a symbol j+9, or a symbol j+5 and a symbolj+6. The symbol j+6 is a sixth symbol counted forward from the symbol j;the symbol j+7 is a seventh symbol counted forward from the symbol j;the symbol j+8 is an eighth symbol counted forward from the symbol j;and the symbol j+9 is a ninth symbol counted forward from the symbol j.For example, if j=9, that is, if the symbol j is a symbol with asequence number #9, the symbol j+5 is a symbol, with a sequence number#0, in a subframe next to a subframe to which the symbol j belongs.

It can be learned that a HARQ RTT is less than 2 ms, far less than 8 msin an existing FDD system. Therefore, a latency is further reduced.

In an embodiment of the present invention, the receiving statusinformation sent by the terminal device is carried on a PUCCH, and theTTI length of the receiving status information is 0.5 ms. In thisapplication scenario, a transmission structure of the PUCCH and a PUCCHDMRS may be the following structure 1 or structure 2.

Structure 1: The PUCCH DMRS is located on the first N symbols of asecond time domain resource (recorded as a timeslot n), the PUCCH islocated on the other 7-N or 6-N symbols of the second time domainresource, and N is 1, 2, or 3. That is, the terminal device sends thePUCCH DMRS in the first N successive symbols of the second time domainresource, and sends the PUCCH in the other symbols of the second timedomain resource. The PUCCH DMRS is used to demodulate the PUCCH.

FIG. 13 is a schematic diagram of a receiving status informationtransmission structure according to an embodiment of the presentinvention. In this embodiment, a normal CP subframe is used as anexample for description, and the normal CP subframe includes 14 symbols.

As shown in FIG. 13, receiving status information occupies one timeslot.The timeslot includes 7 symbols, where the first 2 symbols are used totransmit a PUCCH DMRS, and the last 5 symbols are used to transmit aPUCCH.

After receiving downlink data, a terminal device demodulates thedownlink data and configures the receiving status information based on ademodulation result. Therefore, the terminal device cannot start toconfigure the receiving status information until the downlink datademodulation is completed. However, configuration of the PUCCH DMRS isindependent of a receiving status of the downlink data, that is, theterminal device can start to configure the PUCCH DMRS if the terminaldevice determines that there is downlink data transmitted. Therefore, asending moment of the PUCCH DMRS may be earlier than a sending moment ofthe PUCCH. In this way, more processing time can be reserved for theterminal device.

Structure 2: The PUCCH includes a first PUCCH and a second PUCCH, andthe PUCCH DMRS includes a first PUCCH DMRS and a second PUCCH DMRS.

The first PUCCH and the first PUCCH DMRS are located in the first M1symbols of a second time domain resource in a time domain, and arelocated on a first frequency domain resource in a frequency domain. Thesecond PUCCH and the second PUCCH DMRS are located in the last M2symbols of the second time domain resource in the time domain, and arelocated on a second frequency domain resource in the frequency domain.This embodiment also uses a normal CP subframe as an example fordescription. M1 is 3 and M2 is 4, or M1 is 4 and M2 is 3. When thestructure 2 is used, a frequency domain diversity gain may be obtained,and PUCCH demodulation performance is improved.

Correspondingly, that the terminal device sends the receiving statusinformation to a network device on the second time domain resourceincludes:

sending, by the terminal device, the first PUCCH and the first PUCCHDMRS in the first M1 symbols of the second time domain resource, wherethe first PUCCH and the first PUCCH DMRS occupy the first frequencydomain resource; and sending, by the terminal device, the second PUCCHand the second PUCCH DMRS in the last M2 symbols of the second timedomain resource, where the second PUCCH and the second PUCCH DMRS occupythe second frequency domain resource.

With reference to FIG. 14a to FIG. 14h , a receiving status informationtransmission structure in the structure 2 may include the followingstructures.

As shown in FIG. 14a , FIG. 14b , FIG. 14c , or FIG. 14d , a first PUCCHand a first PUCCH DMRS are located in the first 3 symbols of a secondtime domain resource in a time domain, and are located on a firstfrequency domain resource in a frequency domain; and a second PUCCH anda second PUCCH DMRS are located in the last 4 symbols of the second timedomain resource in the time domain, and are located on a secondfrequency domain resource in the frequency domain.

As shown in FIG. 14a and FIG. 14b , the first PUCCH DMRS may be locatedin a second symbol of the second time domain resource; or as shown inFIG. 14c and FIG. 14d , the first PUCCH DMRS may be located in a firstsymbol of the second time domain resource.

As shown in FIG. 14a , the second PUCCH DMRS may be located in a fifthsymbol and a sixth symbol of the second time domain resource; as shownin FIG. 14b , the second PUCCH DMRS may be located in a fifth symbol ofthe second time domain resource; as shown in FIG. 14c , the second PUCCHDMRS may be located in a fourth symbol and a fifth symbol of the secondtime domain resource; or as shown in FIG. 14d , the second PUCCH DMRSmay be located in a fourth symbol of the second time domain resource.

As shown in FIG. 14e , FIG. 14f , FIG. 14g , or FIG. 14h , a first PUCCHand a first PUCCH DMRS are located in the first 4 symbols of a secondtime domain resource in a time domain, and are located on a firstfrequency domain resource in a frequency domain; and a second PUCCH anda second PUCCH DMRS are located in the last 3 symbols of the second timedomain resource in the time domain, and are located on a secondfrequency domain resource in the frequency domain.

As shown in FIG. 14e , the first PUCCH DMRS is located in a secondsymbol and a third symbol of the second time domain resource; as shownin FIG. 14f , the first PUCCH DMRS is located in a second symbol of thesecond time domain resource; as shown in FIG. 14g , the first PUCCH DMRSis located in a first symbol and a second symbol of the second timedomain resource; or as shown in FIG. 14h , the first PUCCH DMRS islocated in a first symbol of the second time domain resource.

As shown in FIG. 14e or FIG. 14f , the second PUCCH DMRS is located in asixth symbol of the second time domain resource; or as shown in FIG. 14gor FIG. 14h , the second PUCCH DMRS is located in a fifth symbol of thesecond time domain resource.

Referring to FIG. 15, FIG. 15 is a block diagram of a terminal deviceaccording to an embodiment of the present invention. As shown in FIG.15, the terminal device includes a receiver 210 and a transmitter 220.

The receiver 210 is configured to receive at least one piece of downlinkdata on a first time domain resource.

The transmitter 220 is configured to send receiving status informationon a second time domain resource, where the receiving status informationis used to indicate a receiving status of the at least one piece ofdownlink data.

A transmission time interval of the receiving status information isgreater than a transmission time interval of any piece of downlink datain the at least one piece of downlink data, the transmission timeinterval of the any piece of downlink data is less than 1 ms, and a timeinterval between the second time domain resource and the first timedomain resource is less than 4 ms.

Optionally, based on the embodiment shown in FIG. 15, a processor mayfurther be included, where an input end of the processor is coupled withthe receiver, and an output end of the processor is coupled with thetransmitter. The processor is configured to generate the receivingstatus information based on the receiving status of the at least onepiece of downlink data received by the receiver.

Optionally, when the processor is configured to generate the receivingstatus information based on the receiving status of the at least onepiece of downlink data received by the receiver, the processor may bespecifically configured to determine receiving statuses of all downlinkdata in the at least one piece of downlink data, and generate thereceiving status information based on the receiving statuses of all thedownlink data.

It should be noted that how a receiving status of downlink data isdetermined is not limited in the present disclosure, and any manner inwhich whether downlink data is successfully received by the receiver ornot can be determined can be applied in the present disclosure.

In addition, for a manner of generating the receiving status informationbased on the receiving statuses of all the downlink data in the at leastone piece of downlink data, reference may be made to correspondingcontent in the method embodiments. Details are not described hereinagain.

Optionally, the receiver 210 is further configured to: when one or morepieces of downlink data in the at least one piece of downlink data failto be received on the first time domain resource, receive, on a thirdtime domain resource, the one or more pieces of downlink data that areretransmitted by a network device. A time interval between the thirdtime domain resource and the first time domain resource is less than 8ms.

For specific distribution of the first time domain resource, the secondtime domain resource, and the third time domain resource, refer tocorresponding content in the foregoing method embodiments. Details arenot described herein again.

For a receiving status information transmission structure, refer tocorresponding content in the foregoing method embodiments. Details arenot described herein again.

The terminal device provided in this embodiment receives the at leastone piece of downlink data on the first time domain resource; and thensends the receiving status information on the second time domainresource. The time interval between the second time domain resource andthe first time domain resource is less than 4 ms, the transmission timeinterval of the any piece of downlink data is less than the transmissiontime interval of the receiving status information, and the transmissioninterval of the any piece of downlink data is less than 1 ms. When theterminal device transmits data, a transmission time interval of downlinkdata and a time interval between a sending time of the receiving statusinformation and a receiving time of the at least one piece of downlinkdata are shortened, thereby reducing a latency. In addition, thetransmission time interval of the receiving status information (namely,uplink data) is greater than the transmission time interval of downlinkdata. This enhances performance for receiving the receiving statusinformation, and increases a probability that the network devicecorrectly receives the receiving status information returned by theterminal device. In addition, a HARQ RTT is reduced (less than 8 ms),and the latency is further reduced effectively.

Referring to FIG. 16, FIG. 16 is a block diagram of a network deviceaccording to an embodiment of the present invention. As shown in FIG.16, the network device includes a transmitter 310 and a receiver 320.

The transmitter 310 is configured to send at least one piece of downlinkdata on a first time domain resource.

The network device sends the at least one piece of downlink data to aterminal device by using the transmitter 310.

The receiver 320 is configured to receive, on a second time domainresource, receiving status information sent by the terminal device,where the receiving status information is used to indicate a receivingstatus of the at least one piece of downlink data.

A transmission time interval of the receiving status information isgreater than a transmission time interval of any piece of downlink datain the at least one piece of downlink data, the transmission timeinterval of the any piece of downlink data is less than 1 ms, and a timeinterval between the second time domain resource and the first timedomain resource is less than 4 ms.

Optionally, the transmitter 310 is further configured to: when thereceiving status information indicates that one or more pieces ofdownlink data in the at least one piece of downlink data fail to bereceived, retransmit the one or more pieces of downlink data on a thirdtime domain resource. A time interval between the third time domainresource and the first time domain resource is less than 8 ms.

For specific distribution of the first time domain resource, the secondtime domain resource, and the third time domain resource, refer tocorresponding content in the foregoing method embodiments. Details arenot described herein again.

The network device provided in this embodiment sends the at least onepiece of downlink data on the first time domain resource; and thenreceives, on the second time domain resource, the receiving statusinformation sent by the terminal device. The time interval between thesecond time domain resource and the first time domain resource is lessthan 4 ms. In addition, the transmission time interval of the any pieceof downlink data is less than the transmission time interval of thereceiving status information, and the transmission time interval of theany piece of downlink data is less than 1 ms. When the network devicetransmits data, a transmission time interval of downlink data and a timeinterval between a sending time of the receiving status information anda receiving time of the at least one piece of downlink data areshortened, thereby reducing a latency. In addition, the transmissiontime interval of the receiving status information (namely, uplink data)is greater than the transmission time interval of downlink data. Thisenhances performance for receiving the receiving status information, andincreases a probability that the network device correctly receives thereceiving status information returned by the terminal device. Inaddition, the time interval between the third time domain resource andthe first time domain resource is reduced (a HARQ RTT is less than 8ms), and the latency is further reduced effectively.

It should be noted that in this specification, relational terms such as“first” and “second” are only used to distinguish one entity oroperation from another, and do not necessarily require or imply that anyactual relationship or sequence exists between these entities oroperations. Moreover, the terms “include”, “comprise”, or their anyother variant is intended to cover a non-exclusive inclusion, so that aprocess, a method, an article, or an apparatus that includes a list ofelements not only includes those elements but also includes otherelements which are not expressly listed, or further includes elementsinherent to such process, method, article, or apparatus. An elementpreceded by “includes a . . . ” does not, without more constraints,preclude the existence of additional identical elements in the process,method, article, or apparatus that includes the element.

The foregoing descriptions are merely specific implementations of thepresent disclosure. It should be noted that a person of ordinary skillin the art may make several improvements or polishing without departingfrom the principle of the present disclosure and the improvements orpolishing shall fall within the protection scope of the presentdisclosure.

What is claimed is:
 1. A data transmission method, comprising:receiving, by a terminal device and via a downlink channel, at least onepiece of downlink data on a first time domain resource; and sending, bythe terminal device and via an uplink channel, receiving statusinformation on a second time domain resource, wherein the receivingstatus information is used to indicate a receiving status of the atleast one piece of downlink data, a time interval between the secondtime domain resource and the first time domain resource is less than 4milliseconds, a transmission time interval of the uplink channelcarrying the receiving status information is greater than a transmissiontime interval of the downlink channel carrying any piece of downlinkdata in the at least one piece of downlink data, the transmission timeinterval of the downlink channel carrying the any piece of downlink datais less than 1 millisecond; wherein a length of the transmission timeinterval of the downlink channel carrying the any piece of downlink datain the at least one piece of downlink data is one of 2 symbols and 1symbol, and the transmission time interval of the uplink channelcarrying the receiving status information is 0.5 ms; and the first timedomain resource is a timeslot n−2 and the second time domain resource isa timeslot n, wherein the timeslot n−2 is a second timeslot countedbackward from the timeslot n, each of the timeslots consists of 6 or 7symbols, and each of the timeslots has a length of 0.5 ms, and theuplink channel is a physical uplink control channel (PUCCH).
 2. Themethod according to claim 1, wherein the transmission time interval ofthe downlink channel carrying any piece of downlink data in the at leastone piece of downlink data is one of 1, 2, 3, and 4 symbols, and thetransmission time interval of the uplink channel carrying the receivingstatus information is one of 0.5 ms and 1 ms.
 3. The method according toclaim 2, wherein the method further comprises: if the terminal devicefails to receive one or more pieces of downlink data in the at least onepiece of downlink data on the first time domain resource, receiving, bythe terminal device, the retransmitted one or more pieces of downlinkdata on a third time domain resource; wherein the third time domainresource is a timeslot n+2 or a timeslot n+3, the timeslot n+2 is asecond timeslot counted forward from the timeslot n, and the timeslotn+3 is a third timeslot counted forward from the timeslot n.
 4. Themethod according to claim 1, wherein the transmission time interval ofthe any piece of downlink data in the at least one piece of downlinkdata is 0.5 ms, and the transmission time interval of the receivingstatus information is 1 ms; and the first time domain resource is one ofa subframe n−2 and a subframe n−3 and the second time domain resource isa subframe n, wherein the subframe n−2 is a second subframe countedbackward from the subframe n, and the subframe n−3 is a third subframecounted backward from the subframe n.
 5. The method according to claim1, wherein before receiving, by the terminal device, the at least onepiece of downlink data on the first time domain resource, receiving, bythe terminal device, signaling, wherein the signaling indicates at leastone of: a time interval between a second time domain resource and afirst time domain resource, a time interval between a second time domainresource and a third time domain resource, and a time interval between athird time domain resource and a first time domain resource.
 6. Themethod according to claim 1, wherein the transmission time interval ofPUCCH is 0.5 ms, the PUCCH comprises a first PUCCH and a second PUCCH,and a PUCCH DMRS comprises a first PUCCH DMRS and a second PUCCH DMRS;and the sending, by the terminal device, receiving status information ona second time domain resource comprises: sending, by the terminaldevice, the first PUCCH and the first PUCCH DMRS in the first M1 symbolsof the second time domain resource, wherein the first PUCCH and thefirst PUCCH DMRS occupy a first frequency domain resource in a frequencydomain; and sending, by the terminal device, the second PUCCH and thesecond PUCCH DMRS in the last M2 symbols of the second time domainresource, wherein the second PUCCH and the second PUCCH DMRS occupy asecond frequency domain resource in the frequency domain; wherein ifeach timeslot comprises 7 symbols, M1 is 3 and M2 is 4, or M1 is 4 andM2 is
 3. 7. A data transmission method, comprising: sending, by anetwork device and via a downlink channel, at least one piece ofdownlink data on a first time domain resource; and receiving, by thenetwork device and via an uplink channel, receiving status informationon a second time domain resource, wherein the receiving statusinformation is used to indicate a receiving status of the at least onepiece of downlink data; wherein a transmission time interval of anuplink channel carrying the receiving status information is greater thana transmission time interval of a downlink channel carrying any piece ofdownlink data in the at least one piece of downlink data, thetransmission time interval of the downlink channel carrying the anypiece of downlink data is less than 1 millisecond, a time intervalbetween the second time domain resource and the first time domainresource is less than 4 milliseconds; wherein a length of thetransmission time interval of the downlink channel carrying the anypiece of downlink data in the at least one piece of downlink data is oneof 2 symbols and 1 symbol, and the transmission time interval of theuplink channel carrying the receiving status information is 0.5 ms; andthe first time domain resource is a timeslot n−2 and the second timedomain resource a timeslot n, wherein the timeslot n−2 is a secondtimeslot counted backward from the timeslot n, each of the timeslotsconsists of 6 or 7 symbols, and each of the timeslots has a length of0.5 ms, and the uplink channel is a physical uplink control channel(PUCCH).
 8. The method according to claim 7, wherein the transmissiontime interval of the downlink channel carrying any piece of downlinkdata in the at least one piece of downlink data is one of 1, 2, 3, and 4symbols, and the transmission time interval of the uplink channelcarrying the receiving status information is one of 0.5 ms and 1 ms. 9.The method according to claim 7, wherein the method further comprises:if the receiving status information indicates that one or more pieces ofdownlink data in the at least one piece of downlink data fail to bereceived, retransmitting, by the network device, the one or more piecesof downlink data on a third time domain resource; wherein the third timedomain resource is a timeslot n+2 or a timeslot n+3, the timeslot n+2 isa second timeslot counted forward from the timeslot n, and the timeslotn+3 is a third timeslot counted forward from the timeslot n.
 10. Themethod according to claim 7, wherein the transmission time interval ofthe any piece of downlink data in the at least one piece of downlinkdata is 0.5 ms, and the transmission time interval of the receivingstatus information is 1 ms; and the first time domain resource is one ofa subframe n−2 and a subframe n−3 and the second time domain resource isa subframe n, wherein the subframe n−2 is a second subframe countedbackward from the subframe n, and the subframe n−3 is a third subframecounted backward from the subframe n.
 11. The method according to claim7, wherein before sending, by the network device, the at least one pieceof downlink data on the first time domain resource, sending, by thenetwork device, signaling, wherein the signaling indicates at least oneof: a time interval between a second time domain resource and a firsttime domain resource, a time interval between a second time domainresource and a third time domain resource, and a time interval between athird time domain resource and a first time domain resource.
 12. Themethod according to claim 7, wherein the transmission time interval ofPUCCH is 0.5 ms, the PUCCH comprises a first PUCCH and a second PUCCH,and a PUCCH DMRS comprises a first PUCCH DMRS and a second PUCCH DMRS;and the receiving, by the network device, the receiving statusinformation on a second time domain resource comprises: receiving, bythe network device, the first PUCCH and the first PUCCH DMRS in thefirst M1 symbols of the second time domain resource, wherein the firstPUCCH and the first PUCCH DMRS occupy a first frequency domain resourcein a frequency domain; and receiving, by the network device, the secondPUCCH and the second PUCCH DMRS in the last M2 symbols of the secondtime domain resource, wherein the second PUCCH and the second PUCCH DMRSoccupy a second frequency domain resource in the frequency domain;wherein if each timeslot comprises 7 symbols, M1 is 3 and M2 is 4, or M1is 4 and M2 is
 3. 13. A terminal device, comprising: a receiver,configured to receive at least one piece of downlink data on a firsttime domain resource and via a downlink channel; and a transmitter,configured to send receiving status information on a second time domainresource and via an uplink channel, wherein the receiving statusinformation is used to indicate a receiving status of the at least onepiece of downlink data, a time interval between the second time domainresource and the first time domain resource is less than 4 milliseconds,a transmission time interval of the uplink channel carrying thereceiving status information is greater than a transmission timeinterval of the downlink channel carrying any piece of downlink data inthe at least one piece of downlink data, the transmission time intervalof the downlink channel carrying the any piece of downlink data is lessthan 1 millisecond; wherein a length of the transmission time intervalof the downlink channel carrying the any piece of downlink data in theat least one niece of downlink data is one of 4 symbols and 3 symbols,and the transmission time interval of the uplink channel carrying thereceiving status information is 0.5 ms; and the first time domainresource is one of a timeslot n−2 and a timeslot n−3 and the second timedomain resource is a timeslot n, wherein the timeslot n−2 is a secondtimeslot counted backward from the timeslot n, and the timeslot n−3 is athird timeslot counted backward from the timeslot n, each of thetimeslots consists of 6 or 7 symbols, and each of the timeslots has alength of 0.5 ms: or a length of the transmission time interval of thedownlink channel carrying the any piece of downlink data in the at leastone piece of downlink data is 2 symbols or 1 symbol, and thetransmission time interval of the uplink channel carrying the receivingstatus information is 0.5 ms; and the first time domain resource is atimeslot n−2 and the second time domain resource is a timeslot n, eachof the timeslots consists of 6 or 7 symbols, and each of the timeslotshas a length of 0.5 ms, and the uplink channel is a physical uplinkcontrol channel (PUCCH).
 14. The terminal device according to claim 13,wherein the transmission time interval of the downlink channel carryingany piece of downlink data in the at least one piece of downlink data isone of 1, 2, 3, and 4 symbols, and the transmission time interval of theuplink channel carrying the receiving status information is one of 0.5ms and 1 ms.
 15. The terminal device according to claim 13, wherein thereceiver is further configured to: when one or more pieces of downlinkdata in the at least one piece of downlink data fail to be received onthe first time domain resource, receive the retransmitted one or morepieces of downlink data on a third time domain resource; wherein thethird time domain resource is a timeslot n+2 or a timeslot n+3, thetimeslot n+2 is a second timeslot counted forward from the timeslot n,and the timeslot n+3 is a third timeslot counted forward from thetimeslot n.
 16. The terminal device according to claim 13, whereinbefore receiving, by the terminal device, the at least one piece ofdownlink data on the first time domain resource, receiving, by theterminal device, signaling, wherein the signaling indicates at least oneof: a time interval between a second time domain resource and a firsttime domain resource, a time interval between a second time domainresource and a third time domain resource, and a time interval between athird time domain resource and a first time domain resource.
 17. Theterminal device according to claim 13, wherein the transmission timeinterval of the PUCCH is 0.5 ms, the PUCCH comprises a first PUCCH and asecond PUCCH, and a PUCCH DMRS comprises a first PUCCH DMRS and a secondPUCCH DMRS; and the transmitter is specifically configured to: send thefirst PUCCH and the first PUCCH DMRS in the first M1 symbols of thesecond time domain resource, wherein the first PUCCH and the first PUCCHDMRS occupy a first frequency domain resource in a frequency domain; andsend the second PUCCH and the second PUCCH DMRS in the last M2 symbolsof the second time domain resource, wherein the second PUCCH and thesecond PUCCH DMRS occupy a second frequency domain resource in thefrequency domain; wherein if each timeslot comprises 7 symbols, M1 is 3and M2 is 4, or M1 is 4 and M2 is 3.